Yeah, abrasion in some form is going to be what it takes. Sandblasting would sure as heck take even heavy rust off with no problem, if you know someone who could do that for you (though it does leave the surface covered with tiny pits, which may create another set of problems).
Alternatively, I’d equip myself with three grades of water-resistant sandpaper and wet-sand the rust away with the coarser grade, then work through the finer grades to progressively restore a smooth finish.
These would also do the job. They’re rubber blocks embedded with powdered abrasives.
Since you’re going down to bare metal, you’ll have to re-season the wok to prevent it from rusting again.